COL5A1 and Ehlers-Danlos syndrome: The majority of classical EDS cases are caused by mutations in the COL5A1 or COL5A2 genes, which encode type V collagen; vascular EDS is mainly caused by mutations in the COL3A1 gene, which encodes type III collagen; and the genetics of hypermobility-type EDS is estimated to be diverse and not fully clear (Pepin et al., 2000; De Paepe and Malfait, 2012).